The bag can be, in particular, of a side-gusset bag that has longitudinal edges reinforced by weld seams, and that has been sealed shut by a header weld to create a package with an essentially cubical contents space after it is filled. A bag of this type is well-suited for large-volume packages and can be employed, in particular, to package chunk-type, pelletized, or is granular dry food for animals.
Many types of dry animal food are nuggets or granules that sometimes have sharp edges. These press through thin packaging material, thereby creating an uneven surface forming an outside surface of the package. This is found to be objectionable for aesthetic reasons. Thin packaging materials can also be pierced. In addition, the desired shape stability and static stability of the packaging is frequently insufficient. As a result, relatively thick packaging materials are therefore used in practice to produce stabile bags.
JP 2007/230637 discloses a bag made of a multilayer film laminate where an inside surface layer of the bag is made of a foamed polyolefin layer. The foamed polymer layer improves the resistance to penetration. The film laminate is used in particular for infusion solutions.
Published document JP 2004/091024 relates to a vacuum packaging made of a multilayer film that lies tightly against the contents after the packaging has been evacuated such that the shape of the contents is revealed through the film. The contents can involve granular solids, for example granulates. The layered structure of the film used as vacuum packaging comprises a seal layer, a barrier layer, an outer layer, and a foamed layer between the outer layer and the barrier layer.
Published document CA 1 145 724 relates to a vacuum packaging for packaging meat that has not been deboned. A foamed protective film is provided in regions of the packaging that come into contact with bones, the protective film being intended to prevent the outer wrapping of the packaging from being pierced.
Foamed films and multilayer films that have a foam intermediate or core layer have not been considered for bags that form an essentially cubical contents space and must be stable. In light of this fact, the object of the invention is to reduce the use of polymer in a bag for granular or lumpy bulk material and to provide a packaging that has superior shape stability along with low mass per unit surface area for the film, and that is characterized by high mechanical strength. The package should have an outer shape with essentially flat sides, the contents not being revealed on the film sides.